Abstract
What is the nature of practical reason? This is a question that has occupied the minds of Islamic and Western philosophers, and each has answered it based on their own philosophical system. Among the Islamic sages is Qutb al-Din al-Razi, and among the Western philosophers is Baruch Spinoza, who have come forward to answer it. In Qutb al-Din al-Razi's view, reason is a commonality of the two powers of knowledge and action; because the work of theoretical reason is in some way affected by reality and has a passive identity, and the work of practical reason is in some way affected by reality and has an active identity. However, from Spinoza's point of view, the will to know is a confirmation, and confirmation is also a state of complete conception. Therefore, the will is a state of complete conception, and since complete conception is the same as reason. Therefore, the will is the same as reason; accordingly, reason in his thinking is only theoretical reason that only knows and confirms and denies, and he does not accept practical reason in the sense that previous philosophers used to say.

Introduction
The nature of reason, particularly its divisions into theoretical and practical reason, has long been a central concern for philosophers across both Islamic and Western traditions. This question is not merely a matter of abstract philosophical speculation; it has profound implications for understanding human action, ethics, and the very structure of knowledge itself. The distinction between theoretical reason—which seeks to understand reality as it is—and practical reason—which guides action and moral judgment—has been a recurring theme in the history of philosophy. Yet, despite its prominence, the precise nature of practical reason and its relationship to theoretical reason remains a subject of ongoing debate and interpretation.
This article builds upon the foundational work of Professor Abedi Shahroudi, who in his book *The Law of Ethics*, and subsequently in the present author's work on the epistemological presuppositions of the science of conduct (*ilm al-suluk*), explored the reflections of major philosophers from Ibn Miskawayh to Hakim Sabzavari and from Descartes to Kant, seeking to extract their answers to several key questions regarding practical reason. The central question of this inquiry is: What is the nature and existence of practical reason? This question leads to several subsidiary questions: What is the relationship between practical reason and theoretical reason? What is the relationship between practical reason and knowledge (or cognition)? What is the relationship between practical reason and action? What is the relationship between practical reason and will and free will? What is the relationship between practical reason and practical wisdom (*hikmat al-`amaliyyah*)?
This article focuses on explaining the views of two influential philosophers from distinct traditions: Quṭb al-Dīn al-Rāzī, a prominent figure in the Islamic philosophical tradition, and Baruch Spinoza, a major figure in Western rationalism. The study first clarifies the ontological status of reason in the human being according to each philosopher, then examines the division of reason into theoretical and practical, describes the components of practical reason, and finally explains the relationship of practical reason to will and action. The research employs a descriptive-analytical method with rational explanation, and the comparative approach of these two thinkers represents an innovation of this work, as previous studies have typically examined each philosopher separately.

Research Methodology
This research employs a descriptive-analytical and rational-explanatory method within a comparative philosophical framework. The study aims to describe, analyze, and compare the philosophical positions of Quṭb al-Dīn al-Rāzī and Baruch Spinoza on the nature of practical reason, based primarily on Rāzī's commentaries on Avicenna's *Ishārāt* and Spinoza's *Ethics, Demonstrated in Geometrical Order*. The methodology involves a systematic examination of primary texts and their logical implications.
The research proceeds through several stages: first, a textual analysis of the relevant works of each philosopher to extract their explicit statements and implicit assumptions regarding practical reason; second, a reconstruction of each philosopher's conceptual framework concerning the nature of reason, its divisions, and its functions; third, a comparative analysis of the two frameworks to identify points of convergence and divergence; and fourth, an interpretive discussion of the significance of these findings for understanding the nature of practical reason and its role in human life. The analysis is structured around key themes: the nature of reason and its division, the function of theoretical and practical reason, the role of knowledge and perception, the relationship between reason and action, and the relationship between reason and will. The comparative approach is particularly valuable because it brings together two philosophical traditions—Islamic philosophy and Western rationalism—that have developed independently yet address similar fundamental questions about human cognition and action.

Discussion
The Nature of Reason and Its Division: Razi's Distinctive View
In the Islamic philosophical tradition, practical reason (*al-`aql al-`amalī*) has traditionally been understood as a cognitive faculty. It is the faculty by which a human being discerns what they ought to do or avoid in their actions. Practical reason, in this view, functions in the realm of human action and is a form of knowledge about what is good or bad, beneficial or harmful, in practical affairs. Theoretical reason, by contrast, is the faculty by which one apprehends the nature of things as they are, independent of human action. This traditional distinction goes back to Aristotle and was elaborated by Islamic philosophers such as Avicenna and Nasir al-Din al-Tusi.
Quṭb al-Dīn al-Rāzī, however, offers a radically different interpretation of practical reason. In his glosses on the *Ishārāt*, Rāzī challenges the traditional understanding by denying that practical reason has any cognitive or perceptual aspect whatsoever. According to Rāzī, the term "reason" (*`aql*) is applied to two powers—the cognitive power (*quwwah `ālimah*) and the active power (*quwwah `āmilah*)—only in a homonymous sense (*ishtirāk lafẓī*), meaning that the same word is used for two fundamentally different things. The work of theoretical reason, in his view, is to be affected by reality in some way; it has a passive identity. The work of practical reason, by contrast, is to affect reality; it has an active identity.
This means that all forms of perception—whether universal or particular, whether involving deduction or judgment—belong to theoretical reason. Even practical particular judgments (*ra'y juz'ī `amalī*), the specific decisions about what to do in a particular situation, are generated by theoretical reason. The role of practical reason, in Rāzī's account, is not to know or perceive anything but to create and bring about the particular judgment that theoretical reason has formulated. In other words, theoretical reason is the source of knowledge and judgment, even practical judgment; practical reason is the source of action and implementation. The active power—that is, practical reason—is the faculty of decision-making and choice that operates according to the plan established by theoretical reason. It functions as the executor of theoretical reason's commands. Rāzī's definition thus strips practical reason of any cognitive content and reduces it to a purely executive and active faculty. This view represents a significant departure from the standard position in Islamic philosophy and has been influential on later thinkers.
The Epistemological Framework of Spinoza's *Ethics*
Baruch Spinoza's philosophical system, as presented in his *Ethics, Demonstrated in Geometrical Order*, offers a comprehensive metaphysical, epistemological, and ethical framework that significantly differs from the Islamic philosophical tradition in which Rāzī operated. Spinoza's philosophy is built upon the concept of a single substance—God or Nature—that has infinite attributes, of which thought (or mind) and extension (or body) are the two we can comprehend. For Spinoza, the human being is not a composite of two separate realities—mind and body—but a single reality considered under two attributes: thought and extension. The mind is the idea or the thinking aspect of the body, and the body is the object of the mind. This parallelism between thought and extension is fundamental to Spinoza's entire system.
Spinoza divides the mind's functions into two general categories: cognition (knowledge) and affectivity (emotion or feeling). The cognitive structure involves understanding, imagination, reason, and the affirmation or denial of ideas. This structure has three levels: imaginative knowledge (first kind of knowledge), rational knowledge (second kind), and intuitive knowledge (third kind). Imaginative knowledge is confused and inadequate, arising from the senses and imagination; it produces contradictory judgments and leads to error, moral degradation, and human bondage to harmful emotions. Rational knowledge is adequate, arising from reason through common notions—concepts shared by all things—and is characterized by clarity, distinctness, order, and universality. Intuitive knowledge is the highest form of cognition, arising from an adequate understanding of the essence of God's attributes and enabling us to understand the essence and cause of particular things.
The affective structure, or the emotions, arises from how the mind perceives and responds to its environment. Emotions can be classified in two ways: first, they can be active or passive, depending on whether they arise from adequate (active) or inadequate (passive) ideas; second, they are fundamentally composed of three basic emotions—desire, joy, and sadness—from which all other emotions are derived. Active emotions, arising from adequate ideas, lead to human freedom and empowerment; passive emotions, arising from inadequate ideas, lead to bondage and human weakness.
Will, Desire, and the Nature of Practical Reason in Spinoza
Spinoza's account of the will is central to his understanding of practical reason. He analyzes the will in two senses. In the primary sense, the will is the faculty of affirmation and denial, of judgment. This is a cognitive activity and involves the mind's ability to affirm or deny ideas. The will, in this sense, is not a distinct faculty but is identical to the idea itself; every idea, as it is an idea, involves affirmation or denial. In the secondary sense, the will can refer to desire (*appetitus*), which is the striving or conatus of a being to persist in its own existence. However, Spinoza makes a crucial distinction: desire is a confused idea—a desire that arises from inadequate, imaginative knowledge. It is an appetite accompanied by consciousness of itself, and it belongs to the passive emotions, being an affect rather than an act of reason.
Spinoza's central claim concerning the will and reason is that the will, understood as the faculty of affirmation and denial that accompanies adequate ideas, is not distinct from reason. Affirmation, for Spinoza, is a state of complete conception (*conceptus completus*). Since complete conception is identical to reason itself, the will is thus identical to reason. This means that, in Spinoza's framework, reason is purely theoretical reason; it knows, affirms, and denies, but it does not have a separate practical function. Spinoza, therefore, does not accept the notion of practical reason as a distinct faculty, as earlier philosophers understood it. The traditional division of reason into theoretical and practical is rejected. Reason is one and singular: it is the faculty of adequate knowledge, of understanding through the common notions and intuitive knowledge.
How, then, does Spinoza account for action and ethics if there is no distinct practical reason? The answer lies in his theory of the emotions and the role of adequate knowledge in transforming passive emotions into active ones. Rational knowledge—both the second and third kinds—produces active emotions, such as courage (*fortitudo*) and nobility (*generositas*), which are expressions of human freedom. The highest form of active emotion is intellectual love of God (*amor Dei intellectualis*), which arises from intuitive knowledge of God. This love, a joy accompanied by the idea of God as its cause, is not a passive emotion but a pure activity of the mind. It is the summit of human flourishing and brings about true happiness. In this state, the individual is no longer subject to the sway of passive emotions but actively governs them through the power of reason. Thus, while Spinoza rejects practical reason as a distinct faculty, he provides a sophisticated account of how rational cognition can shape action and lead to ethical perfection.
Comparative Analysis: Two Conceptions of Practical Reason
The comparison between Rāzī and Spinoza reveals a fundamental divergence in their understanding of practical reason. For Rāzī, reason is divided into two powers, theoretical and practical, and practical reason is a non-cognitive, executive faculty. For Spinoza, reason is singular, purely theoretical in function (knowing, affirming, denying), and the will, as the active affirmation of adequate ideas, is identical to reason. Spinoza does not accept the traditional division of reason into two distinct faculties. The first point of divergence lies in the very concept of practical reason. Rāzī's practical reason is an active power whose function is to execute the commands of theoretical reason; it has no role in knowledge or perception. It is the source of action, not of judgment or knowledge. Spinoza's rejection of practical reason as a distinct faculty stems from his view that the will, understood as rational affirmation, is identical to reason. Since reason is purely theoretical, there is no room for a separate practical reason. The active dimension of human life is accounted for through the emotions—passive and active—and the role of adequate knowledge in transforming the former into the latter.
Despite these differences, both philosophers see the will and reason as closely connected. For Rāzī, the active power is the executive of theoretical reason and operates according to its plan. However, for Spinoza, the will is not a separate executive but is identical to the mind's activity of affirmation. When the affirmation is rational, it is identical to reason itself. Both philosophers also acknowledge that reason is not merely a passive contemplative faculty; it has implications for action. For Rāzī, this implication is mediated through the active power that executes its commands. For Spinoza, this implication is intrinsic to the nature of adequate ideas, which directly produce active emotions and guide action. The relationship between reason and action is internal to reason itself, not mediated by a separate power.
The third point of difference concerns the nature of the will. In Rāzī's framework, the will is a function of the active power, which is distinct from the theoretical power and exists alongside it. For Spinoza, the will is not a separate power but the act of affirmation and denial, and when this act is rational, it is identical to reason. In other words, Spinoza's will is not something over and above reason; it is reason in its active aspect. In Rāzī's philosophy, practical reason is not merely a synonym for will; it is a distinct faculty with an executive function.
Finally, the two thinkers differ on the role of knowledge in ethics. Both value reason and its capacity to guide human action, but their conceptions of this guidance are fundamentally different. For Rāzī, the guidance comes through theoretical reason's formulation of practical judgments, which are then executed by practical reason (the active power). For Spinoza, ethical guidance comes through the power of adequate knowledge to transform the emotions and produce active, life-enhancing affective states. Spinoza's ethical system is not based on the commands of a separate practical reason but on the rational understanding of reality and the affective transformation that this understanding brings about. This rational understanding, particularly in its highest form of intuitive knowledge, leads to intellectual love of God, which is the ultimate expression of human freedom and ethical perfection.

Conclusion
This comparative study of Quṭb al-Dīn al-Rāzī and Baruch Spinoza on the nature of practical reason reveals two fundamentally distinct philosophical positions. Rāzī, within the Islamic philosophical tradition, distinguishes between theoretical reason and practical reason, defining practical reason as an active, non-cognitive faculty whose function is to execute the judgments of theoretical reason. He strips practical reason of any perceptual or cognitive role, reducing it to an executive power. Spinoza, in contrast, rejects the traditional division of reason into theoretical and practical. For him, reason is singular, purely theoretical, and the will, as the power of affirmation and denial, is identical to reason. The active dimension of human life is accounted for through his theory of the emotions and the role of adequate knowledge in transforming passive emotions into active ones.
The comparison has shown that, although both philosophers address the relationship between reason and action, their conceptions of this relationship are fundamentally different. Rāzī's model is one of hierarchy and division: theoretical reason commands, and practical reason executes. Spinoza's model is one of identity and transformation: reason knows adequately, and this adequate knowledge directly produces active, ethical emotions. The consequences of these different models for understanding human conduct are profound. Rāzī's approach sees practical reason as the servant of theoretical reason, operating in a subordinate role. Spinoza's approach sees reason itself as the source of ethical life, and the highest form of ethical life arises from the most adequate knowledge.
Despite these differences, both philosophers are united in their commitment to the power of reason in guiding human life and in their opposition to pure irrationalism. Both offer sophisticated philosophical accounts of how reason can and should shape human action. This comparative analysis highlights the richness of philosophical discussions on the nature of reason and provides a framework for future research on comparative philosophical approaches to practical reason, ethics, and human conduct. The study also suggests that the Islamic and Western philosophical traditions, though often studied separately, address similar fundamental questions and that comparative analysis can illuminate both traditions. Future research could extend this comparison to other philosophers in both traditions, examine the influence of these thinkers on later developments in ethics and moral psychology, and explore the practical implications of these different conceptions for understanding and cultivating moral agency.